Intercommunication apparatus



Feb.2 6, 1957 R. H. CAMPBELL INTERCOMMUNICATIONAPPARATUS Filed June 30, 1952 IN V EN TOR.

ATTORNEYS United States Patentfi 1 VINTERCOMMUNICATION APPARATUS Richard H; CampbelL'Racine, Wis., assignor to Webster Electric Company, Racine, Wis., a corporation of Delaware 1 Applicafiondune'litl, 1952, Serial No. 296,416

Claims. (Cl. 179-37 in'sucli a system enabling different types of units readily to'becbinbined in' a system.

A 'further object of the present invention is to provide a new and imprdve'dcorrimunication system comprising difi'erent'types crane and having a new and improved arrangement for signallingwhet'her or not a particular station isbusy;

still furtherobject' of the present invention is the provision of a ne'wandimpr'ove'd intercommunication system of the loudspeakin'gtype wherein one or more of the units may beiprovidedwith'hand sets which may be utilized for two-way conversation independently-of the loudspeakingportionof the system.

' Other objects and'advantages of the present invention will become apparent from the'ensuin'g description of an illustrative embodiment thereof in the course of which reference is bad to theaccompanying drawingfthe single figure of which illustrates diagrammaticallya system constructed and arranged in' accordancewith the invention.

Referring now to the drawing, the communication system herein is shown to include four stations numbered 1 to 4, inclusive, of which stations 1 and 2 are identical and =each consists of an intercommunicating unit constructed in accordahcewfith the invention; Stations '3 and 4- have apparatus of-a known typeand which will be described in greater detailhereinafter. I

-The apparatusat station 1 includes an amplifier '10, a loudspeaker 12 utilized both as a receiver and transmitter, 21 multi-position communication-control switch indicated generally by-the reference character 14, two groups of station selector switches 16 and 20, an incomingsignalling control switch means 22, and a hand set 24 provided with a transmitter 26 and a receiver 28.

The amplifieir l fl may-beef any well-known'construction and therefore has not been illustrated in detail. It does include an input transformer winding 30 and an output transformer winding 32. Also shown are the conductors 34 and 36 by means of which the amplifier plate (B) voltage circuit is completed in a manner to be described in detail hereinafter under the control of the switch 14.

The communication control switch 14 includes a number of three-position switch blades indicated by the reference characters 40, 41, 42,43, 44, 45, 46, 47, and 48, all of which are operable simultaneously and which perform the functions now to be described.

The switch blade 40 controls the plate voltage supply to the amplifier, the filaments or heaters of which are normally supplied with power so that when the plate voltage circuit is completed the amplifier is immediately rendered operative.- In the indicated position of switch 14,-

completed through aivoltage reducing resistor 50. As a result of the interposition of'the resistor 50 inthe plate voltage circuit a lesserplate'voltage is applied to the amplifier tubes so that amplification takes place at a lesser gain. a

The communication control switch .14, it should perhaps be noted at this point, is operable into three posi tions, namely an uppeiyt-center, and lower position. The switch is indicated in its central or listen position wherein the amplifier 10 is rendered operative with reduced plate voltage, the loudspeaker 12 is connected to the output and certain intcrstation circuits are connected to the input of the amplifier. Accordingly, in the indicated position, calls coming into station '1 are amplified by the amplifier and supplied to the loudspeaker 12.

In the upper position of switch 14 the circuits are conditioned for what may be called an idle position. In this position the loudspeaker 12 is connected to an interstation circuit individual to station 1, which circuit is indicated by the reference character 51. Incidentally, the interstation circuit individual to station 2 is indicated by the reference character 52', that for station 3 by reference character 53, that'forstation {1 by reference character 54, and that for a 'furtherstation (not shown), but which may be similar in construction to stations 1 and 2, by

reference character 55. v

In the lower, talk, position, the loudspeaker, the amp-lb fier is rendered operative with full plate voltage, the loud resistors 68,71 72, and 74 areshunte-d by a capacitor 80,

and resistors 66, 68, 7G, 72, 74, and 76 by a capacitor 82. The amplifierinput conductors are alsoconnected by branch input conductors 8 0 and 82 to conductors 84 and 86 leading to stationary contacts associated with switch blades .42 to 45, inclusive. Other branch input conductors 88'and 9il le ad to the hand set 24 and a switch 92 associated therewith and including the three movable switch blades 94, 96, and 98 which are in their indicated lower positions when the hand set isnot in use and which are movable re, a'nothe'r'and upper position when the hand set is lifted off 'itscradle for use. i

The interstationj'ci'r'cuit 51 constituting the home line for" station '1 'is connected across resistors and 72 included in the busy sighalmeans, The junction of these tworesisto'rs is connected ,by conductor 100 to the movable sWitch'blade-48 also; constituting part of the busy signal circuit means and vwhich in its indicated and lower (ta-1k) position isjconnected to ground through ground circuit 102. The switch blade/'48 in its upper and idle posit-ion connectsconductor 100'to conductor 104, which in turn is'connected to a busy signal relay 106 also connected by conductor108 to the source of plate voltage (B supply) whereby the relay 106 is energized to hold in its uppermost or. actuated position a switch blade 110. In

its upper 'or' operative position the switch blade 110 completes an energizing circuit for a signal lamp 112 which is thus energized when the relay 106 is ungrounded or when station 1 is not connected to another station whereat a switch-correspondingto 48 grounds the busy signal circuit: t 1

The amplifier output winding 32 is connected to an output circuit: 114,. 116 having connected in series and in parallelg-therewith,:respectively, the impedance matching resistorsllsand 120, and of which the latter is connected to the central contacts associated. with the movable switch blades 42 and 43 of which the latter is connected directly to one terminal of the voice coil 12A of the loudspeaker 12, and of which the former is connected to the other terminal of the coil by conductors 122, the switch blade 98 of the hand set, and conductor 124. Accordingly, in the listen position of the switch 14 it will be noted that the loudspeaker 12 is connected to the output of amplifier 10.

The amplifier output circuit 114, 116 is also connected by the branch conductors 126 and 128 to the lowermost contacts of the movable switch blades 44 and 45, and by branch conductors 130 and 132 to both the lowermost and uppermost contacts associated with movable switch blades 46 and 47.

The movable switch blade 41 is adapted to short circuit resistors 66, 68, 70, 72, 74, and 76 (and thus the input through these resistors) in both the upper, idle, and lower, talk, positions of the switch blade, this being accomplished through the conductors 134 and 136.

As indicated heretofore, the loudspeaker 12 is connected to the output of the amplifier in the indicated listen position of switch 14. In the upper or idle position of the switch the loudspeaker is connected to the home circuit 51 through the switch blades 42 and 43 and conductors 140 and 142. In the lowermost or talk position of switch 14 the loudspeaker is connected to the input of the amplifier through the previously referred to branch conductors 80 and 82 by the switch blades 42 and 43.

The switch blades 44 and 45 are connected to conductors 144 and 146 which constitute a two-way communication circuit (as indicated by the double ended arrow) leading to stations 3 and 4. Connected across this circuit are the resistors 148 and 150, the junction of which is connected to busy circuit conductor 100.

In similar manner switch blades 46 and 47 are connected to conductors 154 and 156 constituting an outgoing circuit (as indicated by the arrow) through which station 1 is placed in transmitting relation to other similar stations, such as stations 2 and 3. The circuit 154, 156 is shunted by the resistors 158 and 160, the junction of which is also connected to the busy circuit conductor 100.

The selective connection of circuit 144, 146 to desired stations is effected through the group of selector switches 16, of which only two are shown, these being indicated by the reference characters 16-4 for station 4 and 16-3 for station 3.

The group of selector switches 20 is shown to include two, namely 20-2 for station 2 and 20-5 for station 5. The switches are all alike and originally are all connected in parallel. In installation a separation between the two groups for the two difierent types of stations is effected by a break B in the circuit.

The apparatus at station 4 is shown as including a loudspeaker 161 having its voice coil connected to the movable switch blades 162. and 164, which normally occupy a position connecting the loudspeaker to the interstation circuit 54 individual to station 4. The switch blades 162 and 164 are movable into a plurality of positions, two as indicated, whereby the loudspeaker can be connected to call in circuits 166 and 168 individual to station 1 and station 2, respectively.

Station 3 includes a multi-position switch 172 normally connecting it to interstation circuit 53 individual to station 3 and shown as being movable into a position to complete a circuit to the call in circuit 166 for station 1. It should be understood that like circuits for other stations including station 2 could be supplied.

When either switch 162 or switch 172 is closed to complete a circuit to the call in circuit such as circuit 166, a buzzer 174 at station 1 is energized, the energizing circuit being completed through the interstation circuit 166, the voice coil of loudspeaker 160 at station 4, and

the movable switch blades 176 and 178 at station 1 of which the former is normally connected to ground through circuit 180 and of which the latter is normally connected to the buzzer through conductor 182 and the secondary winding 184 of a power transformer, the other terminal of the buzzer being grounded. Accordingly, the circuit to the buzzer can be completed through the voice coil at the calling station, thereby to operate the buzzer at station 1 and to produce a sound signal at station 4. The switch 22 at station 1 can be operated into a lower position wherein the circuit 166 is connected to the communication circuit 144, 146 at station 1 through the branch circuit 186. When this is done and the communication control switch 14 at station 1 is left in its indicated listen position, then station 1 can be called by voice signal instead of through, the buzzer. When this is done the branch circuit 186 is connected to circuit 144, 146 and the latter is connected to the input of amplifier 10 through circuits 80, 82 and 60, 62, while the output of the amplifier is connected to loudspeaker 12 at station 1.

The apparatus at station 3 is of a slightly difierent type that is in and of itself of conventional character. Briefly, it includes an amplifier 190 having input and output windings 192 and 194, respectively. These windings are adapted alternately to be connected by a talk-listen switch 196 to a loudspeaker 198 or the switch 172, the switch 196 thus constituting a reversing switch enabling the amplifier to be used for two-way communication.

The apparatus at station 2 is, as heretofore indicated, the same as at station 1 and, consequently it will not be described in detail. It will be noted though that the calling line 168 for station 2 leads to it as does the interstation line 52 constituting the station 2 home line. It is provided with a station selector switch 200 for selecting station 1 and selector switch 202 for selecting station 4. Obviously, other interstation lines and selector switches could be provided.

The hand set 24 at station 1 is normally not in use and in this condition it rests upon its associated cradle, not shown. At this time the switch blades 94, 96 and 98 are in their displaced positions thus disconnecting the transmitter 26 and receiver 28 from associated circuits, and completing a circuit to the loudspeaker 12 as earlier described.

When the hand set is lifted from its cradle for use, the receiver 26 is connected directly to the input of amplifier 10 through the circuit 88, 90 and switch blade 94. The receiver 28 is connected in series with the loudspeaker 12, this connecting being made through conductors 204, 206, the switch blade 98, and conductor 124. The circuit arrangement is such that with the hand set off its cradle and with the communication control switch 14 in its upper idle position, two-way communication without operation of switch 14 is possible with other stations like station 1 (for example, station 2) having individual home lines for reception and outgoing lines.

A brief general description of the system will now be given. While only a few stations have been illustrated, it should be understood that a system ordinarily may have many more. The system may include stations of the type such as stations 1 and 2 having individual home lines and connected through two interstation circuits over which signals are sent in opposite directions. The system may include also stations such as station 3 with which communication is carried on alternately in opposite directions over a single interstation circuit, such as the twoway communication circuit 144, 146. Stations similar to station 4 having no amplifiers may also be utilized and with these communication is carried on in opposite directions over a single two-way interstation circuit, such as 144, 146.

Ordinarily, the system is idle but the amplifiers are supplied with power so as to be ready for operation. The communication control switches 14 will generally be in their upper idle position. In this position, loudspeaker 12 is connected directly to its home line 51 through conductors 140 and 142. Thus, it can be called by voice from other stations having amplifiers such, for example, as station 2. When station 2 calls it by after closure of station selector switch 200, and using its own amplifier, then the'operator at station 1 will respond by closing station selector switch 20-2. Thereafter the communication control switches 14 will be alternately operated between their central listen and lower talk positions. The incoming messages to a station will come in through the home line, be attenuated by the resistor arrangement 64-78, amplified by the amplifier, and reproduced in the loudspeaker. In reverse communication the loudspeaker is connected to the input of the amplifier through conductors 80 and 82 and the output of the amplifier is connected through circuit 154-156, and the now closed station selector switch 20-2 to station 2. V

Station selection is effected with the communication switch 14 in its idle position. In the event that the selected station is not busy, then the relay 106 remains energized and the light 112 remains lighted. However, if the selected station is busy, the relay 106 is connected to ground with the result that the light 112 is extinguished. The ground connection, in the case of selection of a busy station, is through the lowermost switch blade 48 and the busy signal conductor 100 connected to the junctions of the resistors connected across the various interstation circuits. At a busy station the ground line 102 is connected to the corresponding busy signal line 100 so that if an idle station selects a busy station, the relay 106 at the idle station is grounded.

Station 1 can call stations 3 and 4 by voice upon closure of the desired selector switch and operation of the communication control switch 14 to its lowermost talk position. Communication with stations such as station 4 is carried on over circuit 144, 146 alternately in opposite directions under the control of switch 14. Stations such as station 3 require alternate operation of the communication control switches at the two stations between their talk and listen positions.

; Stations'3 and 4 can call station 1 through the buzzer call in line 166. If station 4 calls station 1, a circuit is closed through the buzzer 174, transformer winding 184 and the voice coil of loudspeaker 161 in series. To re spond to such a call the operator at station 1 simply closes the necessary selector switch and thereafter carries on conversation as described earlier. If desired, voice call into stations such as station 1 can be efiected by operation of switch 178 to its lowermost position, thus connecting the call in line 166 to the two-way communication circuit 144, 146.

The hand set 24 can be utilized, and when lifted off the cradle, the transmitter 26 is directly connected to the input of amplifier and the receiver 28 is connected in series with the voice coil of the loudspeaker 12. Accordingly, the hand set may be utilized and the arrangement is such that it can be utilized for two-way communication without operation of the communication control switch 14 if the latter is left in its upper idle position. At this time, reduced plate potential is supplied to the amplifier so that outgoing calls are not amplified as much as they are with the switch in its talk position. Incoming calls are supplied to the receiver 28 with the result that two-way communication over line 51 and line 154, 156 is possible, with the switch 14 in its idle position. It will be noted also that when the switch 14 is in its upper position, the line 154-156 alone is connected to the amplifier output. When the hand set is used the busy signal line is grounded through switch blade 96 so that stations selecting station 1 will get a busy signal.

While the present invention has been described in connection with the details of a specific illustrative embodiment, it should be understood that these details are not intended to be limitative of the invention except insofar as set forth in the accompanying claims.

What is claimed as new and desired to be secured by Letters Patent is: p

l. A communication system including a plurality of stations, an amplifier at each station, a translating device at each station usable both as a receiver and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for each station for reception, an outgoing interstation line from each station for transmission in a two-way interstation line for both reception and transmission, attenuating means at each station, and means including amplifier, device, line and attenuating means circuits and multiposition communication =control switch means controlling said circuits at each station and operable in a first position to connect said device to the incoming line; in 'a second position to connect said incoming line to the amplifier input through said attenuating means, to connect the two-way line to the amplifier input, and to connect the amplifier output to said device; and in a third position to connect said device to said amplifier input and the amplifier output to said outgoing and two-Way lines.

2. A communication system including a plurality of stations, an amplifier at each station, a translating device at each station usablev both as a receiver and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for each station for reception, an outgoing interstation line from each station for transmission and a two-way interst-ation line for both reception and transmission, attenuating means at each station, and means including amplifier, device, line and attenuating means circuits and multipositioncommunication control switch means controlling said circuits at each station and operable in a first position to connect said device to said incoming line; in a second position to connect said incoming line to the amplifier input through said attenuating means, to connect the two-way line to the amplifier input, and to connect the amplifier output to said device; and in. a third position to connect said device to said amplifier input and the amplifier output to said outgoing and two-Way lines, a source of plate voltage for the amplifier at each station, and means including switch means operable simultaneously with said control switch means and circuits controlled thereby for connecting said source to the amplifier in the various positions of said switch means.

3. A communication system including a plurality of stations, an amplifier at each station having a single input, a translating device at each station usable both as a receiver and a transmitter, means inter-connecting said plurality of stations including an interstation incoming line for each station for reception and an outgoing interstation line from each station for transmission, attenuation means at each station, and means including amplifier, device, line and attenuating means circuits and multiposition communication control switch means controlling said circuits at each station and operable in a first position to connect said device to the incoming line; in a second position to connect said incoming line to the amplifier input through said attenuating means and to connect the amplifier output to said device; and in a third position to connect said device to said amplifier input and the amplifier output to said outgoing line.

4. A communication system including a plurality of stations, an amplifier at each station, a loudspeaker type translating device at each station usable both as a receiver and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for each station for reception and an outgoing interstation line from each station for transmission, attenuating means at each station, means including amplifier, device, line and attenuating means circuits and a multiposition communication control switch means controlling said circuits at each station and operable in a first position to connect said device to said incoming line; in a second position to connect said incoming line to the amplifier input through said attenuating means and to connect the amplifier output to said device; and in a third position to connect said device to said amplifier input and the amplifier output to said outgoing line, a hand set at each station including a receiver and transmitter, and n cans including switch means operable by said set and receiver, transmitter and amplifier circuits controlled thereby for controlling said receiver and transmitter, said switch means in one position effectively disconnecting said receiver and transmitter from circuit and in another position connecting said transmitter to the amplifier input for transmission and said receiver to said device for reception.

5. A communication system including a plurality of stations, an amplifier at each station, a loudspeaker type translating device at each station usable both as a receiver and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for each station for reception, an outgoing interstation line from each station for transmission and a two-way line for both reception and t -nsmission, attenuating means at each station, means incl ing amplifier, device, line and attenuating means circuits and a multiposition communication control switch. means controlling said circuits at each station and operable in a first position to connect said device to said incoming line, and the amplifier output to the outgoing line; in a second position to connect said incoming line to the amplifier input through said attenuating means, to connect the two-way line to the amplifier input, and to connect the amplifier output to said device; and in a third position to connect said device to said amplifier input and the amplifier output to said outgoing and twoway lines, a hand set at each station including a receiver and transmitter, and means including switch means operable by said set and receiver, transmitter and amplifier circuits controlled thereby for controlling said receiver and transmitter, said switch means in one position efiectively disconnecting said receiver and transmitter from circuit and in another position connecting said transmitter to the amplifier input for transmission and said receiver to said device for reception.

6. A communication system including a plurality of stations, an amplifier at each station having an input and an output, a translating device at each station usable both as a rece 'er and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for reception, an outgoing interstation line from each station for transmission and two-way interstation line for both reception and transmission, attenuating means at each station conneted to the amplifier input and incoming line, and means including amplifier, device, line and attenuating means circuits and multiposition communication control switch means controlling said circuits at each station and operable in a first position to connect said device to the incoming line, effectively to short circuit the attenuating means, to disconnect the two-Way line from the amplifier and to connect the amplifier output to the outgoing line; in a second position to connect said incoming line to the amplifier input through said attenuating means, to connect said two-way line to the amplifier input, to connect the amplifier output to said device, and to disconnect the outgoing line from the amplifier; and in a third position to connect said device to said amplifier input, to connect the amplifier output to said outgoing and two-way lines, and effectively to short circuit the attenuation means.

7, A communication system including a plurality of stations, an amplifier at each station having an input and an output, a translating device at each station usable both as a receiver and a transmitter, means interconnecting said plurality of stations including an interstation incoming line for reception, an outgoing interstation line from each station for transmission and a two-way interstation line for both reception and transmission, attenuating means at each station comprising a group of series connected resistors connected to the amplifier input and across a portion of which the incoming line is connected, and means including amplifier, device, line and attenuating means circuits and multiposition communication control switch means controlling said circuits at each station and operable in a first position to connect said device to the incoming line, effectively to short circuit the attenuating means, to disconnect the two-way line from the amplifier and to connect the amplifier output to the outgoing line; in a second position to connect said incoming line to the amplifier input through said attenuating means, to connect said two-way line to the amplifier input, to connect the amplifier output to said device, and to disconnect the outgoing line from the amplifier; and in a third position to connect said device to said amplifier input, to connect the amplifier output to said outgoing and two-way lines, and effectively to short circuit the attenuation means.

8. A communication system as claimed in claim 6 including a source of plate voltage at each station for the amplifier thereat, and means including additional switch means operable with said communication control switch means and voltage supply circuits controlled thereby for supplying said amplifier with full plate voltage in the third position and reduced plate voltage in the other positions.

9. A communication system as claimed in claim 6 wherein the interstation circuits at each station have resistance means connected thereacross, the midpoints of which are joined together, wherein additional switch means and grounding circuits controlled thereby are provided for grounding said midpoints in the second and third positions of said control switch means and a normally energized busy circuit indicating relay is connected to said midpoints in the first position.

10. A communication system including a plurality of stations, an amplifier at each station, a translating device at each station usable both as a receiver and a transmitter,

eans interconnecting said plurality of stations including an interstation incoming line for each station for reception, an outgoing interstation line from each station for transmission and two-way interstation line for both reception and transmission, attenuating means at each station, means including amplifier, device, line and attenuating means circuits and multiposition communication control switch means controlling said circuits at each station operable and in a first position to connect said device to the incoming line; in a second position to connect said incoming line to the amplifier input through said attenuating means and to connect the amplifier output to said device; and in a third position to-connect said device to said amplifier input and the amplifier output to said outgoing and two-way lines, and busy circuit indicating means including additional switch means operable simultaneously with said communication control switch means.

References Cited in the file of this patent UNITED STATES PATENTS 

